HELP! I have a old fireplace and it needs updating

It's floor to ceiling brick, dark dingy redish browns brick. I like stone or tile, but will that be ok to put over the brick? I'd hate to paint it years down the road it ends up not so pretty. It's completly flat, no mantle aside from the woodland mantle that says "ROSS" the previous owner's last name. not to mention the large brick wall that has these dinky shelves on it. there is a ledge a foot up extending to the wall and continuing. My BIGGEST concern is these gaps in the brick for vents above the fireplace. are those ok to cover up???